1. Field of the Invention
The present invention relates to a centrifuge rotor, and in particular, to a centrifuge rotor having a drive clutch assembly thereon.
2. Description Of the Prior Art
A centrifuge rotor is an apparatus in which a liquid sample may be subjected to a centrifugal force field. The rotor has a central axial mounting recess provided therein. The recess receives a coupling member, commonly termed a "spud", provided at the top of a drive shaft, thereby to connect the rotor to a source of motive energy.
Coupling a centrifuge rotor to its drive shaft presents unique problems, since it may be required to remove or replace a rotor as frequently as once per run. The drive coupling functions both to center accurately the rotor on the drive shaft and to transmit drive torque to the rotor. The centering function may be accomplished by providing a tapered shaft seat on the top of the drive shaft and by correspondingly tapering the recess in the rotor. For a small angle taper, termed a "locking taper", this arrangement also serves to transmit drive torque to the rotor. Unfortunately, such a locking taper makes removal of the rotor difficult. In situations where frequent rotor removal is required a tapered drive coupling must exhibit a relatively steep angle. Torque transmittal is then dependent upon the downward force exerted on the taper derived from either the weight of the rotor or from another hold-down mechanism.
Since, in the usual case, the rotor is fabricated from materials such as aluminum or titanium, the mass of the rotor is usually sufficient to couple frictionally the rotor to the drive shaft so that torque from the source may be transmitted to the rotor.
Technology is evolving toward the use of non-traditional materials, such as composites, to fabricate centrifuge rotors. A rotor fabricated from such non-traditional materials is lighter in weight and, accordingly, may not have a mass sufficient to couple frictionally such a rotor to the coupling member to effect torque transmission. A rotor fabricated from composite materials is disclosed in copending application Ser. No. 07/664,174, filed Mar. 1, 1991, assigned to the assignee of the present invention. The International counterparts of this application have been published on Feb. 21, 1991 as publication WO 91/02302 and on Sep. 17, 1992 as publication WO 92/15930.
In view of the foregoing it is believed advantageous to provide a rotor with a coupling assembly that permits easy removal or insertion of a rotor without having the transmission of torque limited by the weight of the rotor.